In the preparation of glass fibers for use as reinforcement in rubber, for example in automotive tires, it is conventional to size the glass fibers during forming and subsequently to coat the sized fibers with a coating composition containing a rubber adhesive and a latex coating. The rubber coated cords or strands of glass fibers are then dried and used to prepare fiber glass belts for incorporation into an automotive tire.
Many forming sizes have been disclosed in the art for use in preparing glass fibers into textile strand for various applications. One particularly effective textile forming size disclosed in the art is a starch weaving size disclosed in U.S. Pat. 3,227,192. This size has found particular utility as a textile forming size but is not a particularly suitable forming size for glass fibers used to form textile strands which are to be utilized in rubber reinforcement applications. An exemplary size for use in preparing glass fibers for subsequent coating with elastomeric material is described in U.S. Pat. 3,655,353.